Incidence and risk factors for carbapenem-and multidrug-resistant Acinetobacter baumannii bacteremia in hematopoietic stem cell transplantation recipients

Background: Bacteremia with multidrug-resistant (MDR) Acinetobacter baumannii with carbapenem resistance is an important healthcare-associated infection that increases morbidity and mortality in immunocompromised patients. The aim of this study was to assess the annual incidence and clinical characteristics of such bacteremia and to identify the risk factors for infection in hematopoietic stem cell transplantation (HSCT) recipients. Methods: A retrospective cohort and case-control study was conducted in 483 HSCT recipients between January 2005 and December 2011 at a single tertiary center. Thirty-eight control HSCT patients without evidence of post-transplant infection were matched with 19 patients with bacteremia due to MDR A. baumannii in a 2:1 ratio. Results: The total incidence of carbapenem-resistant-MDR A. baumannii bacteremia was 0.52 cases/10,000 patient-days. In most cases (17 of 19, 89.5%), bacteremia developed after engraftment. Pneumonia was the origin of bacteremia in all patients. Eighteen (94.7%) patients with bacteremia and 3 (8.3%) without bacteremia died. In multivariate regression analyses, the duration between admission and HSCT (odds ratio (OR) 2.19 per 1-day increase, p = 0.030) and a history of care in an intensive care unit after HSCT (OR 32.2, p = 0.021) were independent risk factors for the development of carbapenem-resistant-MDR A. baumannii bacteremia. Conclusions: We report that carbapenem-resistant-MDR A. baumannii bacteremia in HSCT recipients is a fatal infectious complication and mainly develops after engraftment.